That is, pretending to be the Messiah. The warning of v. 5 applies specifically to the fall of Jerusalem and to the Jewish nation, which was particularly susceptible to this form of deception. In the days of the apostles there were many false messiahs. See Josephus, War vi. 5. 4 [312-315]. Later (v. 27), “in unmistakable language, our Lord speaks of His second coming” (DA 631).